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The Binding of Isaac: Rebirth (Windows)

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Title Screen

The Binding of Isaac: Rebirth (Windows)

Developers: Edmund McMillen, Nicalis
Publisher: Nicalis
Platform: Windows
Released internationally: November 4, 2014

AnimationsIcon.png This game has unused animations.
AreasIcon.png This game has unused areas.
CodeIcon.png This game has unused code.
DevMessageIcon.png This game has a hidden developer message.
CopyrightIcon.png This game has hidden developer credits.
DevTextIcon.png This game has hidden development-related text.
GraphicsIcon.png This game has unused graphics.
MusicIcon.png This game has unused music.
SoundIcon.png This game has unused sounds.
DebugIcon.png This game has debugging material.
RegionIcon.png This game has regional differences.
Carts.png This game has revisional differences.

This article is a work in progress.
...Well, all the articles here are, in a way. But this one moreso, and the article may contain incomplete information and editor's notes.
To do:
The USA Wii U version has an Afterbirth executable, despite the fact that Afterbirth wasn't released for the Wii U version. It can be made to work using PC assets.
<Sanky> please suggest an unused sprite with a clock or something
This game is still under active development.
Be aware that any unused content you find may become used or removed in the future. Please only add things to the article that are unlikely to ever be used, or went unused for some time. If they do get used, please remove them from the page and specify in the edit summary!

A remake of The Binding of Isaac, doubling the amount of content, introducing console players to its special brand of dead baby jokes, bringing in an all-new soundtrack courtesy of Ridiculon, and freeing it from the painful bonds of ActionScript 2.0.


Afterbirth is a DLC expansion for Rebirth. They didn't keep the old man!
Afterbirth+, confusing name and all, is a DLC expansion for Afterbirth. Five significant updates were given to it.

Developer Messages

Hidden Message

The following message found in a readme warns hackers not to spoil the game for others.

You might wonder how you can open those .a files. Currently there are no
tools available, and there is a reason to it.

Binding of Isaac: Rebirth has a lot of content that is unlocked as you
progress. It also contains some secrets.
We felt that having a folder with all the spritesheets, cutscene videos,
data files and whatnot would be too tempting for people to ignore.
Finding out things while playing the game, either alone, with friends,
or as part of an online community can be a very rewarding experience. We
don't want to take that away from you.

In case you like reverse engineering and absolutely want to take this
beautiful game apart, we would ask you a few things.
 - Don't release any secrets you find to the internet.
 - Don't publish information on how to open the game's data files.
 - Don't give away the unpacked resources.
The least you can do is wait until the game has been released for a
couple of months, so you don't accidentally spoil it for others.

If you have any questions, write to isaac@nicalis.com.

Source: resources/packed/readme.txt

Cutscene Placeholder Messages

The file that stores information for cutscenes contains "temporary texts" that describe what is happening in most of the cutscenes. However, these are commented out. If you restore them and watch a cutscene in-game, a placeholder screen will appear instead of the cutscene, unless the cutscene itself had no temporary text to begin with. The screen displays a description on a dark gray background that fades to light gray.

Binding of Isaac Rebirth Temp End1.png

ID Ending Description
1 Intro N/A
2 Credits Credits sequence.
3 Epilogue N/A
4 Womb (Eden) Isaac crawls into the big chest, and re-emerges as Eden
5 Womb (Rubber Cement) Isaac finds Rubber Cement in the big chest
6 Womb (Noose) Isaac finds a Noose in the big chest and hangs himself
7 Womb (Wire Coat Hanger) Isaac finds a Wire Coat Hanger in the big chest.
8 Womb (Everything is Terrible) Isaac gets pulled into the chest by mom's hand. Everything is Terrible.
9 Womb (Ipecac) Isaac finds IPECAC in the big chest.
10 Womb (Experimental Treatment) Isaac finds Experimental Treatment in the big chest.
11 Womb (A Quarter) Isaac finds A Quarter in the big chest.
12 Womb (Dr. Fetus) Isaac finds Dr. Fetus in the big chest.
13 Womb (???) N/A
14 Womb (It Lives!) N/A
15 Sheol While Isaac looks at the chest, he cycles through all characters and shows a demonic form of himself. He goes into the chest and closes it from inside.
16 Cathedral Isaac is seen reading the bible. He looks into the mirror and sees a demonic form of himself.
17 Chest A bunch of polaroid photos from Isaac's childhoold are shown.
18 Dark Room A telephone pole in front of Isaac's house shows a missing poster featuring Isaac.
19 Mega Satan Isaac is inside the chest and randomly flashes from his normal form to a demon form.
20 Blue Womb Chest with Isaac's remains. Isaac in a chest, his shadow transforms into a demon.
21 Greed Mode Isaac dies and turns into a keeper.
22 The Void N/A
23 Greedier N/A

Source: resources/cutscenes.xml

Unused Rooms

These are rooms that are not associated with any floor, so they will never be encountered.

DEFAULT_0 test room

Room Type: DEFAULT
Room ID: 0
Room Name: test room
The first room in the game by ID. Contains 12 random items and 8 random trinkets.

Source: resources/rooms/00.special rooms.stb

DEFAULT_1 New Room

Room Type: DEFAULT
Room ID: 1
Room Name: New Room
The second room in the game by ID. Contains 4 Gaping Maws and many spikes.

Source: resources/rooms/00.special rooms.stb

Unused Graphics


Objects that are placed in a grid-like fashion, such as rocks, are referred to as grid objects. With that being said, there's a lot of unused grid objects.

Source: resources/gfx/grid/rocks_(Floor).png

Early Tinted Rocks

Most of the floors' rock tilesets have early tinted rock graphics. These conspicuous tinted rocks are very similar to the ones used in the original game.

IsaacRebirth tintedrock burning.png
Flooded Caves
Burning Basement Depths
Dank Depths
Secret Room

Unused Tinted Obstacles

There are tinted versions of every chapter-specific obstacle, but none of them are used in the game. Interestingly, the icons for The Catacombs and The Necropolis Steam achievements use these.

IsaacRebirth tinted burning.png
IsaacRebirth tinted flooded.png
Basement Cellar Burning Basement Caves Catacombs Flooded Caves Depths
Dank Depths
Cathedral Secret Room

Early Indestructible Rocks

Early versions of the indestructible rocks,used in prototype versions of the game.

Basement Cathedral

Half Black Heart


A half-heart version of the black heart. It's not even coded as an existing entity.

Source: resources/gfx/items/pick ups/pickup_001_heart.png

The Jar Expansion

IsaacRebirth thejar rebirth.png
IsaacRebirth thejar afterbirth.png
Prior to Afterbirth Prior to Booster Pack 5

Prior to Booster Pack 5, The Jar had frames for holding up to 10 hearts! After the sprite was redone the second time in Booster Pack 5, these extra frames were removed.

Source: resources/characters/costumes/costume_rebirth_90_thejar.png

Breath of Life

IsaacRebirth breath front.pngIsaacRebirth breath side.pngIsaacRebirth breath back.png

Breath of Life initially had a different animation, almost exactly alike to Chocolate Milk's effect. However, this animation has one frame of Isaac holding his breath that isn't found in Chocolate Milk's spritesheet. It even has its own .anim2 file, paralleling Chocolate Milk's. The finished effect for Breath of Life is a gradual change of Isaac's skin tone, from perky pink to hold-my-breath blue.

Sources: resources/characters/costumes/costume_breath_of_life.png, resources/characters/costumes/costume_breath_of_life_(COLOR).png

Angel Boss Names

Image files: \gfx\ui\boss\vsnames.png

Placeholder names for the two Angel bosses -- actually named "Uriel" and "Gabriel" in the game's entities2.xml configuration file -- for use on the Boss Vs. screen. Since the bosses are immediately spawned by bombing the angel statue, they don't get an intro and these names are never used or needed.

Florian Himsl

Image file: \gfx\cutscenes\intro6.png

Florian Himsl is still on the intro image, right next to Edmund McMillen, but is never shown in-game.

Tear Cursor

Binding of Isaac Rebirth Other Cursor.png
Image file: \gfx\ui\cursor.png

By enabling the Mouse Cursor mode on the game's "options.ini", it shows the cursor with four arrows (the one on the left). The "classic" Windows cursor is never used.

Cage Vomit

Rebirth-Cages vomiting attack.png
Image file: \gfx\bosses\rebirth\boss_090_fatty2.png

In The Cage's spritesheet, there are several unused sprites that actually turn out to be the boss Mega Fatty's vomit-beams, only recolored. Due to the fact that The Cage doesn't necessarily have a head at all, this is possibly the reason why these sprites for one of the boss's attacks are cut out.

Steven's Gemini Leftover

Image file: \gfx\bosses\rebirth\boss_013_steven.png

As uninteresting as it is, it's still an unused leftover from Gemini.

Sisters Vis

IsaacRebirth bossname sistervis.png
Image file: \gfx\ui\boss\bossname_sisterssvis.png

Boirebirth 1980.png
Image file: \gfx\ui\achievement\achievement_sistersvis.png

There is an entry for "Sister Vis" within Rebirth's boss name texture file. Sisters Vis also has an unlock screen texture and noted out achievement prerequisites.

<!-- beat Sheol 10 times -->
<!--<achievement id="179" text='You unlocked "Sister's Vis" in Sheol' gfx="Achievement_SistersVis.png" />-->

Sisters Vis was finally finished for the Afterbirth+ DLC, but they don't have to be unlocked, don't appear in Sheol, and are called "Sisters Vis" in the boss screen, not "Sister Vis."


Image files: \gfx\grid\grid_pressureplate.png

This button/pressure plate was officially implemented in the Afterbirth update, but it's been coded and usable since day one.

This early version of the button acts like a test object for the room lock buttons and random spawn buttons in Afterbirth, though what the button spawns is different as well.

Effect Approximate
Nothing 35%
Spawn a random chest 29%
Spawn 6 Attack Flies 20%
Spawn 6 Troll Bombs 10%
Activate Curse of Darkness for the rest of the floor 3%
Spawn a random pickup 2%
Spawn 15 random coins 1%

If there are any enemies in the room, the button can't be pressed -- this includes the flies that the button spawns.

Original Book of Belial

Binding of Isaac Rebirth Original BookOfBelial.png
Image file: \gfx\ui\giantbook\giantbook_006_bookofbeast.png

Found on the "giantbook" folder (on-screen animations that are shown when using certain items) contains the book from Book of Belial from the original game. The file name of the image is different than the actual item.

Unused Gamma Menu

Binding of Isaac Rebirth GammaOption.png
Image file: \gfx\ui\main menu\gammamenu.png

Graphics found on the main menu folder contains a more advanced gamma settings. In-game, you can only change the gamma and that's it, and pressing on the option won't cause the menu to change to another, since it's implemented inside the "Options" menu. It also has its own animation file.

Unused Item on the Collection Page

Binding of Isaac Rebirth Missing Poster Collection.png
Image file: \gfx\ui\death items.png

On the collection page image, the last item seems to be a "Missing Poster", however, the Missing Poster is a trinket item in the game, so this icon is never seen on the Collection table or when the game is paused. Strangely enough, the item isn't found just next of the previous item in the sheet image, it actually breaks a line after the Dog Food (last item seen in-game via the menu).

Unused Exploded Doors

Binding of Isaac Rebirth burst curse room.png
Image files: \gfx\grid\door_[Floor Number]_[Floor Name].png

In-game, when Isaac drops a bomb on a door, the door will explode and will load a different sprite (a burst door), letting the player skip the room. However, not all doors from all floors can be destroyed with bombs. In the game files, almost every (except the Devil Room door) single door has a burst sprite. This is likely a result to copy and paste data (since most of these has the "Basement" coloring scheme), not matching the special door associated with it.

However, doors for "Curse Rooms", "Arcade Rooms" and doors from the "Chest" and "Dark Room" rooms have burst sprites, even though none of these are possible to explode. The Dark Room doors is actually a complete copy and paste from the Sheol Room, however the game loads the door_21_darkroomdoor and not the one from Sheol. Images were cropped to only show the burst part of these sprite sheets. In order: Curse Room, Arcade Room, Dark Floor Room and Chest Floor Room.

Unused Dice Room Door

Binding of Isaac Rebirth dice room door.png
Image file: \gfx\grid\door_25_diceroomdoor.png

It seems that originally, the Dice Room door would have a red-ish scheme (somewhat similar with the color scheme from the Womb/Utero). This change was probably made for the player to not know the existence of the room unless they open it with two keys (in-game, both Library and Dice Rooms requires two keys to open, and the Dice Room does not have any special color, it uses the color from the current floor).

Unused Fistula Section

Image file: \gfx\bosses\classic\boss_025_fistula.png

An unused section for Fistula. It fits between the medium and smallest sections.

Unused Peep Expressions

Image file: \gfx\bosses\classic\boss_027_peep.png

Unused expressions for Peep.

Mega Satan Skeleton Hand

Image file: \gfx\bosses\rebirth\megasatan2.png

A skeletal version of Mega Satan's hand. The hand never spawns in his skeletal form, rendering this unused.

Unused Floors

By disabling the invalid seed check and using an invalid seed, you can continue the game after the Chest and Dark Room, up to a whooping additional 14 floors! They use pre-existing graphics and the same layout.

A similar feature like this was added in the Afterbirth+ DLC, allowing you to continue the game multiple times after beating the Lamb.

Unused Item Pools

A few unused item pools exist, with some even existing since Rebirth. Despite this fact, they've all been updated to contain Afterbirth+ items. All existing pools can be seen in Afterbirth and onward by picking Chaos.

Key: Rebirth, Afterbirth, Afterbirth+

Source: resources/itempools.xml


An item pool containing bomb related items.

Boom! Mr. Boom Mr. Mega Bobby-Bomb Bomb Bag
Remote Detonator Bob's Curse Butt Bombs Sad Bombs Mama Mega!
Fast Bombs


An item pool containing... even more bomb related items.

Boom! Mr. Boom Mr. Mega Bobby-Bomb Bomb Bag
Remote Detonator Bob's Curse Butt Bombs Sad Bombs Bomber Boy
Scatter Bombs Sticky Bombs Curse of the Tower No. 2 Explosivo
Glitter Bombs Fast Bombs


An item pool containing Mom-related items.

Lunch Dinner Dessert Breakfast Rotten Meat
Mom's Underwear Mom's Heels Mom's Lipstick Mom's Bra Mom's Pad
Mom's Eye Mom's Bottle of Pills Mom's Contacts Mom's Knife Mom's Purse
Mom's Coin Purse Box Mom's Key Mom's Eyeshadow Mom's Wig
Mom's Perfume A Snack Mom's Pearls Mom's Box Moldy Bread
Mom's Razor

Regional Differences


Aside from the obvious change in language, the Korean secrets (in-game achievements) use different images for Cat Got Your Tongue and Everything is Terrible 2. Interestingly Ultra Greed has a beard like in early screenshots.

English Korean
Cat Got Your Tongue IsaacRebirth-secret-161eng.png IsaacRebirth-secret-161kor.png
Everything is Terrible 2 IsaacRebirth-secret-246eng.png IsaacRebirth-secret-246kor.png

Unused Audio

The Binding of Isaac: Rebirth has some unused audio found with the help of Afterbirth+ modding tools.

Early Boss Rush Outro

An early outro for the track 'Ambush' played in the Boss Rush room.

Early Angel Room Appearance Jingle

Oldest version of the jingle that plays when an Angel Room appears.